低バックグラウンド液体シンチレーション計数法の薬学への応用第2 報 尿中内因性~(14)C の変動

摘要

The intra-day, inter-day and individual variations in endogenous 14C radioactivity of human urine were studied by use of 5 mL urine. The endogenous 14C radioactivity of human urine is relatively constant (approximately 1.5 dpm/mL urine). In order to eliminate the effect of endogenous ~(40)K it is of the greatest importance to count ~(14)C signal with the optimal window. Since these variations are relatively small, we can estimate correctly the net ~(14)C activity from the BG value of the same time zone of the day before dosing.